Phantoms still go for above $50 each on Ebay... Add shipping and insurance, that's a lot of booster packs.
On the other side, don't forget that at least YOU can go to a store and pick-up some booster packs if you want. I simply wish I could. I find it much better to buy a handfull of packs every now and then, rather than having to order huge boxes to offset the cost of shipping. There's two advantages, first, it does not seem so costly if you buy only like $20 worth of packs every few days. You spread the joy of opening them. You get to introduce one or two new cards in you deck from time to time until the next few days. And you can stop anytime if you're happy with your deck or money is thight. This bring the second point. In my case, I just want about 5 cards badly right now. So I would rather fish for them every few days, and stop when I get a few of them (would be happy to get any 3), rather than having to order big boxes, and either find them in the first few packs, or as you said yourself, opening them all at once, and finding I've none.